During the procedure of testing a computer program, Graphic User Interface (GUI) test is an important part. GUI test may find problems that might cause a user's incorrect operation or inconvenience in operation in GUI of the computer program. A typical type of such a problem is character truncation. A GUI may include many character regions for indicating user to operate. Representation of a character region in computer program is just visual object(s) and character string(s) associated therewith. During development of a computer program, matching between display size setting of a character string and that of a visual object might be ignored. While translating the computer program from one language into another, actual display size of the character string may change. All of these reasons may cause character truncation. Character truncation may make some characters become invisible on the GUI, so that it fails to effectively direct the user's operation.